The present invention is directed to eyeglasses with removable and interchangeable lenses and a removable and interchangeable nosepiece, an eyeglass system based on the eyeglasses, a method for assembling the eyeglasses, and a method for positioning and securing additional bifocal segments to the eyeglass lenses.
Manufacturing eyeglasses can be a costly and time-consuming process. The eyewires must be fitted so that the optical centers of the lenses are aligned with the patient""s eyes. The patient""s prescription is defined by the pupillary distance, the distance between the patient""s pupils, and spherical and cylindrical corrective factors. Lenses that provide cylindrical correction, unlike purely spherical lenses, must maintain alignment along a prescribed axis that varies from patient to patient. Therefore, in manufacturing traditional prescription glasses, the lenses must be ground to fit the eyewire and also correctly oriented based on their spherical and cylindrical properties.
Preparing prescription glasses includes the process of marking and layout to determine optical center and cylindrical axis of the lens. The lenses are then traced and cut to the shape of the eyewire. If the geometric center of the eyewires does not match the optical center position of the lenses, the lenses are ground to change the position of the optical center in a process called decentration. Finally, the lenses must be beveled and mounted to the eyewires. Any errors made during this process usually cannot be corrected and the process must begin anew. Often a defect in lens manufacturing cannot be discovered until the optometrist verifies that the glasses fit the patient""s prescription. Errors discovered at this point may take weeks to correct.
Interchangeable lenses are known in the prior art. U. S. Pat. No. 5,293,185 (the ""185 patent) discloses an xe2x80x9cEyeglass Eyewire Permitting Interchanging Lensesxe2x80x9d utilizing a spring loaded closure for securing the lenses within the eyewires. What is needed beyond the ""185 patent is an interchangeable prescription lens system that does not require the lenses to go through marking, layout, tracing, cutting, decentration, and beveling, allowing optical dispensers to provide prescription glasses to their patients in a matter of minutes. An interchangeable nosepiece which can change lens decentration without recutting the lenses is also needed. Furthermore, a need exists for an interchangeable prescription lens system that can provide glasses, including bifocals, in the areas of temporary prescriptive eyewear, optical retail environments, military field environments requiring rapid replacement of eyeglasses, and remote locations where standard optical manufacturing is impractical.
An apparatus meeting the above stated needs is an Interchangeable Lens Eyeglass System with Interchangeable Nosepiece comprising a nosepiece coupled to a pair of annular eyewires, and a pair of clasps hinged to the nosepiece that cooperate with each of the two annular eyewires to secure the lenses. Each clasp and eyewire contains a locking hole into which a pin may be inserted to secure the clasp in the closed position. The eyeglasses also contain a pair of temples, each of which is pivotally joined to each of the eyewires. The eyewires have axial markings that indicate the cylindrical axis of the lenses, and bifocal markings that indicate the correct position of the bifocal segments so that lenses may be installed and removed without the need for instruments or tools.
Additionally, a method for assembling eyeglasses in the Interchangeable Lens Eyeglass System with Interchangeable Nosepiece is disclosed. The method consists of selecting a pair of lenses from an inventory of circular lenses according to a patient""s prescription. The circular lenses have the same geometric and optical center, so they do not require decentration by grinding. The round shape also allows the lenses to be rotated within the eyewires when the clasps are open. The lenses are mounted into the annular eyewires of the eyeglasses, rotated so that the cylindrical axis is appropriately aligned, and secured in place so that the lenses may not rotate. The correct pupillary distance is achieved by varying the width of the nosepiece. Bifocal lenses may be selected based on the patient""s bifocal prescription and positioned on the existing lens according to the bifocal markings on the eyewires.